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Could you go into more detail about what you see as issues with IO bound tasks? My understanding is that MRI Ruby provides non-block IO operations if you wrap

by Lio 6y ago

Could you go into more detail about what you see as issues with IO bound tasks? My understanding is that MRI Ruby provides non-block IO operations if you wrap them in a thread and that it is only CPU bound tasks that are blocked by the GVL. Is there some other issue related to that? (JRuby provides fully multi-threading for cpu bound tasks without GVL).

dosethree 6y ago
"My understanding is that MRI Ruby provides non-block IO operations if you wrap them in a thread and that it is only CPU bound tasks that are blocked by the GVL." All IO operations in ruby are subject to the GIL (global interpreter lock).
- Lio 6y ago
  GVL is an implementation detail rather than a feature of the language (I believe the term Global VM Lock replaced GIL in the standard library, sometime around ruby 2.0ish I think). JRuby, for example, has no GVL including for CPU based code; everything there can run in parallel. Even in MRI Ruby though, wrapping IO operations in a thread allows you to release the GVL when the IO operation blocks. e.g. 5.times.map do Thread.new do Net::HTTP.get('example.com', '/index.html') end end.each(&:join) Will perform those network requests in parallel rather than sequencially. This is how ActiveRecord can perform asynchronous database calls in parallel on MRI Ruby. I got that HTTP example from[1], which has a good write up but it's also covered in Working with Ruby Threads by Jesse Storimer[2]. I asked the original question because in the Concurrent-Ruby Readme they discuss Ruby's mutable references and the possibility of thread safety issues because of that.[3] 1. https://pawelurbanek.com/ruby-concurrent-requests https://pawelurbanek.com/ruby-concurrent-requests 2. https://www.goodreads.com/book/show/17826435-working-with-ruby-threads https://www.goodreads.com/book/show/17826435-working-with-ru... 3. https://github.com/ruby-concurrency/concurrent-ruby https://github.com/ruby-concurrency/concurrent-ruby

by Lio 6y ago

dosethree 6y ago

"My understanding is that MRI Ruby provides non-block IO operations if you wrap them in a thread and that it is only CPU bound tasks that are blocked by the GVL." All IO operations in ruby are subject to the GIL (global interpreter lock).

Lio 6y ago
GVL is an implementation detail rather than a feature of the language (I believe the term Global VM Lock replaced GIL in the standard library, sometime around ruby 2.0ish I think). JRuby, for example, has no GVL including for CPU based code; everything there can run in parallel. Even in MRI Ruby though, wrapping IO operations in a thread allows you to release the GVL when the IO operation blocks. e.g. 5.times.map do Thread.new do Net::HTTP.get('example.com', '/index.html') end end.each(&:join) Will perform those network requests in parallel rather than sequencially. This is how ActiveRecord can perform asynchronous database calls in parallel on MRI Ruby. I got that HTTP example from[1], which has a good write up but it's also covered in Working with Ruby Threads by Jesse Storimer[2]. I asked the original question because in the Concurrent-Ruby Readme they discuss Ruby's mutable references and the possibility of thread safety issues because of that.[3] 1. https://pawelurbanek.com/ruby-concurrent-requests https://pawelurbanek.com/ruby-concurrent-requests 2. https://www.goodreads.com/book/show/17826435-working-with-ruby-threads https://www.goodreads.com/book/show/17826435-working-with-ru... 3. https://github.com/ruby-concurrency/concurrent-ruby https://github.com/ruby-concurrency/concurrent-ruby